The presence of misfolded proteins in the endoplasmic reticulum (ER) activates a signaling network called the unfolded protein response (UPR). Although a major target of the UPR is a set of ER chaperones, the mechanisms by which the UPR may contribute to improve protein folding and trafficking remains unclear. The yeast ABC transporter, Yor1 is an ideal model to study the role of UPR in protein folding and export form the ER because the mutant variant Yor1.670, is known to be misfolded, retained in the ER, and targeted for degradation. This study proposes to address three key aspects: (1) does stress activation of UPR promote refolding and export;(2) is UPR alone sufficient to rescue folding;and (3) if not, which other cell components are required. Protein folding status will be assessed by trypsin digestion assays and blue native PAGE while export will be monitor by budding reactions. Microarrays and genetic approaches will be used to identify targets responsible for refolding and enhanced export. UPR activation is not a practical treatment for diseases related to abnormal protein folding since sustained activation induces apoptosis. However, thorough examination of the UPR related components that might be implicated in protein folding will give us a broader view of how these specific targets improve aberrant protein biogenesis in conditions that do not demand ER stress.